An intercept is the point of intersection. A yy-intercept is the point that a line (in this case, the line y=2y=2) intersects the yy-axis.
The yy-intercept for the y=2y=2 graph is simply the point (0,2)(0,2).
Typically, to find a yy-intercept, we would set xx equal to zero and solve for yy...But here, we don't have an xx-term. The given line is y=2y=2 , which tells us that for any xx, no matter how infinitely large or small, yy will always be 2. So, intuitively, we know that when xx is zero, yy is 2...giving us the yy-intercept of (0,2)(0,2). Note that since this is a horizontal line, there is no xx-intercept.